On Fri, 6 Aug 2004, Gene Heskett wrote:> > Linus, Andrew, should I apply this patch too at the next remake?

Might be worth it, but it's more important to see any oops at all, or lack of oopses..

> FWIW, I'm still up (20:38) this morning, and showing plenty (127+ > megs) of free memory. No crash, no odd log (other than samba > squawking about some option thats been changed & I haven't fixed the > smb.conf) so far.> > I'm beginning to like this test patch, Linus, thanks :)

If the only thing you have done is add the list_del_init() debugging patch, then the only thing that has changed is really the access patterns to uncached memory.

The original list_del_init() tries to only do a few single _writes_ to the dentries around it. The added debugging will do _reads_ (and thus bring it into the cache) of the dentry pointers of the dentries around it.

If that change makes a real difference, I really only see two possibilities: - there really is a prefetch bug (or possibly, there's a bug in our prefetch fixup code, and the known prefetch bug just triggers the problem indirectly) - it just changes the timing enough that whatever bug you hit went away.

Now, Chris Shoemaker reported dentry problems on a intel CPU and said that wli had seen something too, but I'm wondering whether Chris and wli might have been seeing the knfsd/xfs-related dentry bug that I found yesterday. So I think the prefetch theory is still alive, but we should check with Chris. Chris?